Refrigerating cycle apparatus

Abstract

A refrigerating cycle apparatus is equipped with a plurality of outdoor units, each of which includes at least one high-pressure type compressor with refrigerant and lubricating oil stored therein. A discharge pipe of the respective compressor is connected to a main discharge pipe for jointly discharging refrigerant and oil to the indoor unit. A suction pipe of the respective compressors is connected for returning the refrigerant and the oil from the indoor unit to the compressor. Each outdoor unit comprises a first oil balancing circuit connected between a side surface of the casing of the respective compressor and the main discharge pipe for allowing a flowing-in of the exceeding oil from the casing of the compressor. In another embodiment, each outdoor unit may include a second oil balancing circuit connected between a side surface of the casing of the respective compressor and the main suction pipe.

The invention claimed is: 
     
       1. A refrigerating cycle apparatus with a plurality of outdoor units each of which is equipped with at least two high pressure type compressors and an outdoor controller, each of the high pressure type compressors having a casing stored with an oil; a discharge pipe; and a suction pipe, a main discharge pipe to which the discharge pipe of the at least two high pressure type compressors is connected, the main discharge pipe and the discharge pipe adapted to jointly discharge refrigerant and oil to at least two indoor units, and a main suction pipe to which the suction pipe of the at least two high pressure compressors is connected adapted to return the refrigerant and the oil from the at least two indoor units to the compressors,
 wherein each one of the plurality of outdoor units comprising:
 an oil balancing circuit into which flows, from each of the respective at least two compressors, an excess amount of the oil stored in the casing of the respective compressor, including: 
 a first exceeding oil passage connected in fluid communication between a side surface of the casing of each one of the respective at least two compressors and the main discharge pipe, the first exceeding oil passage including for each one of the compressors a first oil balancing pipe connected to the side surface of each one of the compressors and a second oil balancing pipe, the second oil balancing pipes are joined together at a third oil balancing pipe which is connected to the main discharge pipe; 
 a first solenoid valve interposed in the third oil balancing pipe in the first exceeding oil passage controlling flow of the exceeding oil from each one of the respective at least two compressors to the main discharge pipe; 
 a second exceeding oil passage connected in fluid communication between the side surface of the casing of each one of the respective at least two compressors and the main suction pipe, the second exceeding oil passage including for each one of the compressors the first oil balancing pipe, a capillary tube, and a fourth oil balancing pipe, the fourth oil balancing pipes are joined together at a fifth oil balancing pipe which is connected to the main suction pipe; 
 wherein for each one of the compressors the first oil balancing pipe is branched into the second oil balancing pipe of the first exceeding oil passage and the capillary tube of the second exceeding oil passage; and 
 a second solenoid valve interposed in the fifth oil balancing pipe in the second exceeding oil passage controlling flow of the exceeding oil from each one of the respective at least two compressors to the main suction pipe, and 
 
 wherein the outdoor controller controls operations of the first solenoid valve and operations of the second solenoid valve. 
 
     
     
       2. The refrigerating cycle apparatus according to  claim 1 , wherein in the case that the plurality of outdoor units are operated and at least one of the high pressure type compressors is running continuously longer than a second predetermined time, each outdoor controller of the plurality of outdoor units which are operated opens the second solenoid valve for a third predetermined time, closes the second solenoid valve, opens the first solenoid valve for a first predetermined time, and then closes the first solenoid valve. 
     
     
       3. The refrigerating cycle apparatus according to  claim 1 , wherein each of high pressure type compressors is equipped with an oil level sensor which detects an oil level of the oil stored in the casing of the respective compressor. 
     
     
       4. The refrigerating cycle apparatus according to  claim 3 , wherein in the case that the plurality of outdoor units are operated and at least one of the oil levels which are detected by the oil level sensors of the at least two high pressure type compressors is below a predetermined level, each outdoor controller of the plurality of outdoor units which are operated opens the second solenoid valve for a third predetermined time, closes the second solenoid valve, opens the first solenoid valve for a first predetermined time, and then closes the first solenoid valve. 
     
     
       5. The refrigerating cycle apparatus according to  claim 2 , wherein after closing the first solenoid valve, the outdoor controller further opens the second solenoid valve for the third predetermined time, and then closes the second solenoid valve. 
     
     
       6. The refrigerating cycle apparatus according to  claim 2 , wherein the outdoor controller controls operations of the first solenoid valve and operations of the second solenoid valve by means of the following successive steps:
 opening the second solenoid valve for the third predetermined time; 
 closing the second solenoid valve after opening the second solenoid valve for the third predetermined time; 
 opening the first solenoid valve for the first predetermined time after closing the second solenoid valve; 
 closing the first solenoid valve after opening the first solenoid valve for the first predetermined time; 
 opening the second solenoid valve for the third predetermined time again after closing the first solenoid valve; and 
 closing the second solenoid valve after opening again the second solenoid valve for the third predetermined time.